Hi, a question for ST3 gurus.

I try to use the new async event listener in various plugin and have some issues beginning with this one:
When async event is called, the underlying view could have been modified, which is perfectly understandable.
But in some case, it look like the view is in a closing state, where lot of it’s method isn’t available.

With this code:

[code]import sublime, sublime_plugin

class ExampleCommand(sublime_plugin.EventListener):
def on_load_async(self, view):
print(view.file_name())[/code]
If I open the Goto Anything (ctrl+p) panel and slowly navigate among unopened files, the filenames are printed in the console.
If I navigate quickly among unopened files, the filenames is replaced with a None in the console.

It’s probably because the view is already closed before the event is triggered.
My question is:
How I can detect that the view is in a closing state ?

Thanks for your help.

Changed the topic’s title, I think it’s a bug, or at least a shortcoming that need a solution.
If an event is triggered with a view argument, the view must be fully accessible or there must be a way to check the state of the view.

This isn’t a bug.

In an async event, Views can be closed at any time, which will render the view_id invalid. This causes all methods to return default values instead. You can test for this by seeing if buffer_id() returns 0, although I’ll add a more explicit function in the next build.

Thanks for the answer.

I tried many things to find a way to detect a closed view, but I missed buffer_id().

I think also that a function in the View class with a explicit name will be very welcomed.
A note in the documentation (http://www.sublimetext.com/docs/3/porting_guide.html) could be useful too.

Also, keep in mind that testing for buffer_id() (or later, is_valid()) intrinsically suffers from a race condition: it can return True, but the View can still be closed before the next statement of your plugin runs. Essentially, if is_valid() returns False, then the View is definitely invalid, but if it returns True, then it may or may not be valid by the time the plugin runs.

argh, I’ve just hit this case.
The on_load_async check buffer_id() before running a plugin method, but the buffer_id() change to 0 during the processing.

There’s something I don’t fully understand here:
Is this behavior limited to the async events ?
Does the non async events run in the main thread (or block other threads) ?
If I replace the on_load_async by a on_load, does the view could change before the on_load finish ?

on_load blocks the whole application while it runs, so the view won’t be closed or otherwise modified underneath you.

If you’re only doing a small amount of processing, then on_load is fine (not to mention simpler), however if you’re doing a lot of processing, or any IO at all, then you’ll make things slow by doing it in on_load

We have save problem, we doing long time running process in on_xxx_async() event with a with RLock: statement, and after the View closed, the thread who running the on_xxx_aync() event seems be killed without RLock be released. So other thread will be blocked forever. Could we have a event to be send a notification if a thread was killed?